Hi everyone, I was trying to solve this problem, and I have tried four different accepted ways

But none of them is faster than 50ms, this is very slow according to the statistical result.

Any advice how to improve?

```
class Solution(object):
def isPowerOfTwo(self, n):
"""
:type n: int
:rtype: bool
"""
## recursive
if n==0:
return False
elif n==1:
return True
elif n%2!=0:
return False
else:
return self.isPowerOfTwo(n/2)
## count bit
return n>0 and len([i for i in range(32) if (1&n>>i)])==1
## 2**30 math
return n>0 and (1073741824 % n == 0)
## n-1 trick
return n>0 and n&(n-1)==0
```